- A
newgrp -g 1500 developers; adduser alice developers
Why wrong: newgrp changes the current group for a session, not for permanent group creation.
- B
create group developers gid=1500; useradd -G developers alice
Why wrong: The command 'create group' is not a valid Linux command.
- C
groupadd developers -g 1500; usermod -G developers alice
Why wrong: usermod -G (without -a) replaces supplementary groups, which could remove alice from other groups.
- D
groupadd -g 1500 developers; usermod -aG developers alice
Correct: groupadd creates the group with GID 1500, usermod appends alice to the supplementary group.
Question 4 of 513
LFCS User and Group Management Practice Question
This LFCS practice question tests your understanding of user and group management. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
A system administrator needs to create a new group named 'developers' with GID 1500 and add the user 'alice' to this group. Which set of commands accomplishes this?
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
groupadd -g 1500 developers; usermod -aG developers alice
Option D is correct because `groupadd -g 1500 developers` creates the group with the specified GID, and `usermod -aG developers alice` adds the user 'alice' to the supplementary group 'developers' while preserving her existing group memberships (the `-a` flag is essential with `-G` to avoid overwriting them). This matches the requirement exactly.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
newgrp -g 1500 developers; adduser alice developers
Why it's wrong here
newgrp changes the current group for a session, not for permanent group creation.
- ✗
create group developers gid=1500; useradd -G developers alice
Why it's wrong here
The command 'create group' is not a valid Linux command.
- ✗
groupadd developers -g 1500; usermod -G developers alice
Why it's wrong here
usermod -G (without -a) replaces supplementary groups, which could remove alice from other groups.
- ✓
groupadd -g 1500 developers; usermod -aG developers alice
Why this is correct
Correct: groupadd creates the group with GID 1500, usermod appends alice to the supplementary group.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often forget the `-a` flag with `usermod -G`, assuming `-G` alone appends, when in fact it replaces all supplementary groups, leading to unintended removal of existing group memberships.
Trap categories for this question
Command / output trap
The command 'create group' is not a valid Linux command.
Detailed technical explanation
How to think about this question
The `-g` flag in `groupadd` specifies the GID, which must be unique and typically above 1000 for user-defined groups on modern systems (per /etc/login.defs). The `-a` (append) flag in `usermod` is critical when using `-G` because without it, `usermod` overwrites the user's supplementary group list; this is a common source of accidental group removal in production environments. The group membership is stored in /etc/group, and changes take effect immediately for new logins, but existing sessions must re-authenticate (e.g., via `newgrp` or logging out) to see the new group.
KKey Concepts to Remember
- Read the scenario before looking for a memorised answer.
- Find the constraint that changes the correct option.
- Eliminate answers that are true in general but not in this case.
TExam Day Tips
- Watch for words such as best, first, most likely and least administrative effort.
- Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A practitioner preparing for the LFCS exam encounters this exact type of scenario on the job. The correct answer here is not the most general option — it is the best answer for the specific constraint described. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Real exam questions reward reading the full scenario before eliminating options, because the constraint defines which answer fits.
What to study next
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
- →
User and Group Management — study guide chapter
Learn the concepts, then practise the questions
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FAQ
Questions learners often ask
What does this LFCS question test?
User and Group Management — This question tests User and Group Management — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: groupadd -g 1500 developers; usermod -aG developers alice — Option D is correct because `groupadd -g 1500 developers` creates the group with the specified GID, and `usermod -aG developers alice` adds the user 'alice' to the supplementary group 'developers' while preserving her existing group memberships (the `-a` flag is essential with `-G` to avoid overwriting them). This matches the requirement exactly.
What should I do if I get this LFCS question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Last reviewed: Jul 4, 2026
This LFCS practice question is part of Courseiva's free Linux Foundation certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the LFCS exam.
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